Patent GB-803020-A (GB)
Title: Improvements in and relating to a drilling machine
IPC: B23Q35/02
Filed: 1955-05-02
Abstract: 803,020. Drilling-machines. FRAUTSCHI, A., and MONNEY, L., [trading as POSALUX, FRAUTSCHI & MONNEY]. May 2, 1955 [May 8, 1954], No. 12635/55. Class 83 (3). A drilling-machine comprises a lever 21 controlling a feeler 20 engaging a jig 5 on the table 3 and a switch 27, closed by the lever, for controlling feed of the quill 7 through a fluidoperated piston 16. The table 3, supporting the jig 5 and work 4, is freely mounted on balls 2 for movement horizontally in two mutually perpendicular directions in relation to a post 2<SP>1</SP>, to locate the work by the centring-action of the feeler 20 engaging openings in the jig. After depressing the hand-lever 21 to centre the jig and locate the work, additional pressure on the lever 21, which is pivoted on the upper-end of the feeler and also connected by a link 23 to a plunger 24 for operating the switch 27, raises the plunger against its return-spring 25 and closes switch 27, which controls, through a relay 28 (Fig. 5, not shown) and a pair of valves, the admission of compressed air to a cylinder 17, above the piston 16, the piston-rod 14 of which feeds the quill 7 through a link 15 and a lever 9. Compressed air also enters a cylinder 34 above a piston 33 on the feeler to hold the latter in position, and a holding-contact, in parallel with switch 27 and closed by energization of the relay, remains closed even if switch 27 opens. The lever 9 is pivoted at 10 to the quill and connected at the adjacent end to a micrometer adjusting-screw 13. The speed at which the quill is lowered, is reduced for the drilling operation when the head 36a of a rod 36 carried in the piston-rod 14 displaces an annular dashpot piston 39a to force oil, from a space 40 beneath the piston, past an adjustable throttlevalve 43 into an auxiliary chamber, from which it returns to the space 40 via a non-return valve 45, upon return of the piston. Displacement of the piston 39a, which is effected by contact between the head 36a and a spring 37 engaging the bottom 38 of a sleeve 39 projecting from the piston, is also resisted by the progressive compression of a spring 47, which is weaker than spring 37 and acts in the space 40. A handoperated switch in the circuit to the relay is also provided, and a further switch 49, operated by an abutment 50 carried by the piston-rod 14, stops the feed when the quill is in its lowermostposition. Drilling long holes. At the end of the stroke of the piston-rod 14, greater resistance is produced by the spring 47 than the strength of spring 37, and hence the latter spring is compressed. This enables the head 36a to open a switch 46 on the sleeve 39, which breaks the circuit of the relay and operates the valves to supply compressed air beneath the piston 16, through a pipe 19. The withdrawal stroke is terminated and the feed stroke re-commenced when the head 36a moves away from the switch 46 and allows it to close and again energize the relay. It is stated that these reciprocations of the piston, and thus of the drill, are repeated during the drilling, presumably with increasing feed produced by the adjusting-screw 13.